Question 1172382
<pre>
Here are all the ways the 4 people could be lined up at random with a girl
at an end:

BBGG  <--girls not separated
BGBG  <--girls separated
GBBG  <--girls separated
GBGB  <--girls separated
GGBB  <--girls not separated

That's 3 ways out of 5, or a probability of 2/5.

Edwin</pre>